Mumford & Sons win top prize at the Grammys

The triumphant march across America of Mumford & Sons continued last night, when they won the Album of the Year award at the Grammy awards in Los Angeles for their second album, Babel.

"We figured we weren't going to win anything because the Black Keys have been sweeping up all day, and deservedly so," said lead singer Marcus Mumford, accepting the award from Adele.

Babel sold 600,000 copies in the US the week it was released, last autumn, and has gone on to rack up more than 1.7m sales, making it the fourth best selling of 2012 in the US. The award to the Mumfords follows a recent Grammy trend of rewarding younger artists – the previous winners of the best album award have been Adele (2012), Arcade Fire (2011) and Taylor Swift (2010). Two of this year's other best album nominees – Fun and Frank Ocean – were on the list for debut album. Of the five, only Jack White had been up for the gong before.

Mumford & Sons' rise in the US has been steep and spectacular, with the band marking the 2011 Grammys, when they appeared as Bob Dylan's backing band, as a key moment. "I think it introduced us to people who watch [awards] shows the way we grew up watching music on TV," keyboard player Ben Lovett told the Los Angeles Times. "It makes sense that it would widen our audience. But we weren't thinking about that at the time."

Indeed, the contrast between the opening week of Babel and that of their debut, Sigh No More, could hardly be greater. That first album sold 5,000 copies in the US in its opening week, entering the charts at No 127. By the 2012 Grammys, though, they had secured four nominations and Sigh No More has now sold more than 2.5m copies, with Mumford & Sons leading a wave of hugely popular roots influenced acts, including the Lumineers and the Avett Brothers. As Billboard put it: "Mainstream rock music, specifically that being consumed in the United States, has rearranged its profile to allow for banjo breaks."

That Billboard report highlighted the group's willingness to play outside the major markets as crucial to their widespread success, and suggested it had been modelled in part on the Avett Brothers' strategy.